function externalLinks() 
{
    if (!document.getElementsByTagName) return;
    var anchors = $A(document.getElementsByTagName("a")).map(Element.extend);
    anchors.each
    (
        function(anchor)
        {
            if (anchor.getAttribute("href") && anchor.getAttribute("rel") == "external")
                anchor.target = "_blank";
        }
    );
}